Date of Award

Spring 2009

Document Type

Legacy Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

College

College of Science

First Advisor

Karen M. Aguirre

Second Advisor

Erin J. Burge

Third Advisor

Vladislav Gulis

Abstract

Microbial sand content contributes to beach quality and may negatively impact human health. To quantitate and identify fungi along a continuum of human use, beaches ranging from pristine to heavy-use areas were studied. If abundance of fungi correlates with recreational use, greater values were predicted for colony forming units per gram of dry weight (CFU g-1dw) in sand samples from high-use beaches than those from low-use beaches. Additionally, higher CFU g-1dw values were expected in samples taken at the end rather than at the beginning of the tourist season (Memorial Day-Labor Day). Sand samples were obtained at triplicate sites 15 m apart and above the high-tide line, in plastic tubes inserted to equivalent 10 cm depth, at nine beaches at three predicted levels of use, in May, July and September. A census of beach users was made at each collection. Samples were partitioned for dry weight measure, and for plating washes on Rose Bengal agar, at 24°C and 37°C. After 5 days CFU g-1dw was calculated. Values were log-transformed and compared by two way full factorial ANOVA (a= 0.05). The ITS-5.8S-ITS2 regions of rDNA from yeast-like 37°C cultures were amplified and determined sequences were compared to known fungi in the BLAST database. Average CFU g-1dw were greater in samples from high-use beaches than in samples from low-use beaches (p< 0.05), but between low-and moderate-use and between moderate-and high-use beaches, only a trend of increased CFU g-1dw was observed. Regression analysis showed significant positive correlation between actual user census per site and CFU g-1dw, but CFU g-1dw was highest before tourist season. Five species with 37°-growth capability were identified. A positive correlation between beach use and fungal abundance suggests an anthropogenic impact on this system, but conflicting results indicate further study is needed to understand beach use effects and non-anthropogenic environmental effects on fungal abundance. The presence of several species with pathogenic potential shows modest diversity in this arid, carbon-poor sand ecosystetn, and merits further study.

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